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wen.sun

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VCO with bond wire inductor
Nov 25^th, 2008, 7:37pm

I am trying to design a 1.8G VCO with bond wire inductor. Some papers shows that the inductance is 1nH/mm. But if considering the mutual inductor, the inductance will decrease a lot?

for example, if the two bond wires are used for inductor, one from die pad to leadframe, and the other from leadframe to die pad. if the distance of die pads is 500um and the distance between die edge and lead is 1mm. Considering the loop height, the bondwire length is about 1.4mm. if k=30%, and M=1.4nH*30%=0.42nH. the total inductor is L+L-2*M=1.4+1.4-2*0.42=1.96nH。

so if consider the mutual inductor, the bondwire inductance is only 0.7nH/mm.

ADS simulation shows a less inductor, why? bond wire height from ground plane is considerd by ads?

Am i right? and how much is the inductance range of bond wire in VCO.

Welcome discussion!

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pancho_hideboo

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Re: VCO with bond wire inductor
Reply #1 - Nov 26^th, 2008, 5:20am

wen.sun wrote on Nov 25^th, 2008, 7:37pm:

ADS simulation shows a less inductor, why? bond wire height from ground plane is considerd by ads?

What do you mean by "ADS simulation" ?
EMDS ? or Simple circuit simulation using passive component library such as following ?

http://www.designers-guide.org/Forum/YaBB.pl?num=1206929207/0#3

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wen.sun New Member Offline Posts: 3	Re: VCO with bond wire inductor Reply #2 - Nov 26^th, 2008, 5:58pm BONDW_Shape and BONDW2 in Passive-RF Circuit Library
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pancho_hideboo

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Re: VCO with bond wire inductor
Reply #3 - Nov 27^th, 2008, 8:45pm

wen.sun wrote on Nov 26^th, 2008, 5:58pm:

BONDW_Shape and BONDW2 in Passive-RF Circuit Library

What procedure do you use to confirm Ltot=L1+L2-2*M ?

V1=j*omega*L1*I1 + j*omega*M*I2
V2=j*omega*M*I1 + j*omega*L2*I2

L(=L1=L2) should be evaluated like following.
� L1=V1/(j*omega*I1) at I2=0

M should be evaluated like following.
�M=V2/(j*omega*I1) at I2=0

Then set I1=I, I2=-I.
�Ltot=(V1-V2)/(j*omega*I)
Did you compare this Ltot with L1+L2-2*M ?

wen.sun wrote on Nov 25^th, 2008, 7:37pm:

how much is the inductance range of bond wire in VCO.

I can't understand a meaning of your question ?
If you use small chip die compared to package and use long wire, you can get large inductance.
Or you mean inductance range for 1.8GHz VCO ?
If so, it depends on requirement Quality factor and frequency variable range.

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« Last Edit: Nov 28^th, 2008, 7:49pm by pancho_hideboo »

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weber8722

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Re: VCO with bond wire inductor
Reply #4 - Mar 17^th, 2009, 7:43am

wen.sun wrote on Nov 25^th, 2008, 7:37pm:

I am trying to design a 1.8G VCO with bond wire inductor. Some papers shows that the inductance is 1nH/mm. But if considering the mutual inductor, the inductance will decrease a lot?

for example, if the two bond wires are used for inductor, one from die pad to leadframe, and the other from leadframe to die pad. if the distance of die pads is 500um and the distance between die edge and lead is 1mm. �Considering the loop height, the bondwire length is about 1.4mm. if k=30%, and M=1.4nH*30%=0.42nH. the total inductor is L+L-2*M=1.4+1.4-2*0.42=1.96nH。

so if consider the mutual inductor, the bondwire inductance is only 0.7nH/mm.

ADS simulation shows a less inductor, why? bond wire height from ground plane is considerd by ads?

Am i right? and how much is the inductance range of bond wire in VCO.

Welcome discussion!

I think your values look fine, 1nH/mm is pretty close to reality in many cases and k=0.3 too.

Bye Stephan

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